Patent GB-251295-A (GB)
Title: Improvements relating to pulverising mills
IPC: B02C25/00
Filed: 1926-04-24
Abstract: 251,295. International Combustion Engineering Corporation, (Assignees of Raymond, F. I.). April 34, 1925, [Convention date]. Roller - and ring mills; ; feeding-devices for granular and like materials.-A pulverizing-mill with means for exhausting air and pulverized material from the mill is provided with feed - regulating means comprising a pneumatic device, an electrically - actuated device for controlling the operation of the feeding-apparatus, and a circuit-making and breaking device for the electrically - actuated device comprising a. vessel having a pair of spaced contacts and containing a conducting fluid, and means operated by the pneumatic device for imparting rocking movements to the vessel. In the mill shown, the material is pulverized between a ring 11, Fig. 1, and a number of centrifugal rollers 12 which move against the inside of the ring. the material being fed into the mill from a hopper 16 by a rotary pocket-feeder 17 mounted on a shaft 18 carrying a ratchet-wheel 19 driven by a pawl 20 pivoted to an arm 21 on a lever 22 which is fulcrummed on the shaft 18 and oscillated by a pitman 24 and crank 25. When the mill overloads, the pawl 20 is disengaged, from the wheel 19 owing to the energizing of a solenoid 26, Figs. 2 and 3, in the circuit of which is a pneumatically-operated contact-breaker 27 which responds to changes of pressure in the upper part of the mill, transmitted to the breaker through a pipe 28. The yoke-like pole-piece, 29 carrying the coil 26 of the solenoid is secured to uprights 31 on the lever 22, and the core 32 of the solenoid has aT-head 33 perforated for guide-studs 34 on the lever 22. A stud 35 at the top of the core passes through the top of the piece 29 and is secured to a yoke 36 into which projects a semicircular block 37 on the end of a stud 38 fixed to a boss 39 on the pawl 20. When the coil is energized, the armature 32, 33 is pulled up against the pole-piece 29 and yoke 36 and lifts the block 37, thereby disengaging the pawl 20. Figs. 4, 5 and 6 show the contact-breaher which controls the current supply to the coil 26. A casing 41 has an interior flange 43 to which is secured a flexible diaphragm 44, and the chamber 45 is connected by a flexible tube 46 with the pipe 28, Fig. 1. A bridge 47 having a central aperture 48 and formed with a pair of spaced webs 49, 50 extends across the casing at the outer side of the diaphragm. A carrier 52 straddling the bridge and pivoted to the web 49 has clips 53, to hold a tube 54 containing mercury, and a pair of legs 55 extending on opposite sides of the bridge with their lower ends clamped against a, spacing-block 56. A pair of contacts 60 in the tube 54 are connected by wires 60 to binding-posts 62 which extend through the casing and receive the lead wires 63 of the coil 26. In one tilted position of the carrier, the mercury completes the circuit between the contacts 60, and in the other tilted position the circuit is broken. A link 67 is pivoted to one end of a bell-crank 65, pivoted on the bridge 47, and to a button 68 on the diaphragm 44. The threaded end 69 of the button extends through the diaphragm and a rigid disc 70 on the inside of the diaphragm, and is secured thereto by a nut 71. A link 72 connects the other end of the bell-crank with a stud 73 on the rocking member. To adjust the circuit-breaker to operate at different degrees of vacuum and to prevent it from being affected by slight pressure changes, a pivoted lever 76 in the chamber 45 bears at one end against the end of the bolt 69 and at the other end is acted upon by a spring 80 adjustable by means of a screw 82. When the mill overloads, the vacuum in its upper part is intensified and the diaphragm 44 is drawn into the chamber 45, thereby rocking the bell-crank 65 and tilting the tube 54 so that the mercury therein closes the circuit through the solenoid. When the mill has cleared, normal pressure is re-established in the chamber 45 and the circuit-breaker is operated to break the circuit, thereby allowing the pawl 20 to re-engage the ratchet 19 .